Magnetic Recording Medium Amorphous Barrier Layer Thermal Stability
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Solution Overview
Problem
High-temperature heating of substrates during the formation of magnetic recording layers leads to degradation of SNR and OW characteristics due to the coarsening of crystal grains in soft magnetic layers, which are unable to maintain amorphous or microcrystalline structures.
Innovation Solution
A magnetic recording medium comprising a substrate with a soft magnetic underlayer containing Fe, B, and elements like Nb, Zr, Mo, or Ta, an amorphous barrier layer with Si, W, and additional elements like Nb, Zr, or Ta, and a magnetic recording layer with an L10 structure, where specific compositional ranges and thicknesses of these layers are optimized to maintain structural integrity and reduce coercive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the substrate is heated to a high temperature (500°C or higher) during the formation of the magnetic recording layer, then the order parameter of the alloy is improved, but the soft magnetic layer is unable to maintain the amorphous or microcrystalline structure, causing crystal grain coarsening and increased coercive force
Solution Approach 1:
An amorphous barrier layer is introduced between the soft magnetic underlayer and the magnetic recording layer. This barrier layer acts as an intermediary that protects the soft magnetic underlayer from direct exposure to high temperatures during the formation of the magnetic recording layer, thereby maintaining the amorphous or microcrystalline structure of the soft magnetic layer while still allowing the magnetic recording layer to achieve the necessary order parameter
Solution Approach 2:
The composition of the soft magnetic underlayer is optimized with specific ranges of B (12-16 at%), Si (5-15 at%), and elements from Nb, Zr, Mo, and Ta (3-12 at% each) to enhance thermal stability. The amorphous barrier layer contains Si (10-30 at%) and W (20-60 at%) with elements from Nb, Zr, Mo, and Ta (5-35 at% each) to maintain structural integrity at high temperatures. These parameter changes enable the layers to withstand thermal processing without degradation
2Reliability
If the soft magnetic layer is heated to a high temperature, then the magnetic recording layer can be formed with improved alloy order, but the soft magnetic layer becomes crystalline with coarse grain structure, degrading SNR and OW characteristics
Solution Approach 1:
The amorphous barrier layer serves as a protective intermediary that prevents thermal damage to the soft magnetic underlayer during high-temperature processing. This allows the magnetic recording layer to achieve the desired alloy order while the soft magnetic layer maintains its fine-grained amorphous or microcrystalline structure, preserving SNR and OW characteristics
Solution Approach 2:
The invention uses a composite multi-layer structure consisting of a soft magnetic underlayer with specific Fe-B-Si-M alloy composition and an amorphous barrier layer with Si-W-M composition. This composite structure combines the thermal stability of the barrier layer with the soft magnetic properties of the underlayer, enabling high-temperature processing without compromising performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed structure improves SNR and OW characteristics by maintaining the amorphous or microcrystalline structure of the soft magnetic underlayer and barrier layer, even at high temperatures, thereby enhancing the thermal stability and surface smoothness of the magnetic recording medium.
Implementation Method 1
the amorphous barrier layer includes Si, W, and one or more elements selected from the group consisting of Nb, Zr, Mo, and Ta... maintaining the amorphous or microcrystalline structure of the soft magnetic underlayer, even at high temperatures
Implementation Method 2
a content of B is in a range of 12% by mol to 16% by mol, and a content of Si is in a range from 5% by mol to 15% by mol... reduce the coercive force of the soft magnetic layer
Data Source
AI summary
A magnetic recording medium includes a substrate; a soft magnetic underlayer laminated on the substrate; an amorphous barrier layer laminated on the soft magnetic underlayer; and a magnetic recording layer laminated on the amorphous barrier layer, wherein the soft magnetic underlayer includes Fe, B, Si, and one or more elements selected from the group consisting of Nb, Zr, Mo, and Ta, wherein the amorphous barrier layer includes Si, W, and one or more elements selected from the group consisting of Nb, Zr, Mo, and Ta, and wherein the magnetic recording layer includes an alloy having an L10 structure.